Limiting Reagents in a Bottle Rocket
Chemistry
Period 1
Crater High School of Business, Innovation, and Science
Josiah Abrams, Malen Mohr, Chase Cavallaro
February 26, 2016
Introduction
Bottle rockets are basic air-propelled rockets. To maintain stability every rocket’s center
of gravity must be in front of the center of pressure, or the rocket will become unpredictable
(nasa.gov). In this experiment playdough was used to change the center of mass and increase
stability. Rockets consist of a body, nose cone, and fins. For the rockets in this lab, the body, or
the soda bottle, consisted of polyethylene terephthalate ((C10H8O4)n) (spaceflightsystems.grc).
The nose cones and fins of a rocket reduce air resistance, but a rounder nose cone is ideal when
the speed of a rocket is slower than the speed of sound (sciencelearn.org). The rocket used in
this lab had a pointed-tipped nose cone for aesthetic purposes.
Newton’s third law states, for every actions there is an equal and opposite reaction.
Rockets are propelled when gas is expelled behind the rocket creating a force that pushes the
rocket forward (quest.nasa.gov). In this lab the propellant was CO2, which was produced
through an acid-carbonate reaction, while the reactants were citric acid (C6H8O7), or vinegar
(HC2H3O2), and baking soda (NaHCO3). The chemical formula for vinegar and baking soda is
HC2H3O2 (aq) + NaHCO3 (aq) → NaC2H3O2 (aq) + H2O (l) + CO2 (g) (scienceline.ucsb.edu).
The formula for citric acid and baking soda is C6H8O7 (aq) + 3NaHCO3 (aq) → Na3C6H5O7 (aq)
+ 3CO2 (g) + 3H2O (l) (Bonuccelli). Citric acid was chosen as the reactant instead of vinegar
because it produces three times the amount of CO2. The amount of baking soda (26.2g) and
citric acid (19.9g) was determined by using all of the remaining funds, and using enough of each
reactant to produce the same amount of propellant.
The purpose of this lab was to build the most cost effective rocket by flying the highest
and staying within budget. This lab provides experience with stoichiometry and insight into the
challenges of engineering.
Materials
Table 1. Materials and Cost
Materials
Trial Run
1 liter bottle
Baking soda (NaHCO3)
Citric Acid (H3C6H5O7)
Cost
250,000
10,000/g
20,000/g
Cork
Cardboard
50,000
12,000/cm2
Duct tape
Paper Towel
10,000/cm
35,000
Launch Pad
Generously Donated
Final Run
1 liter bottle
Baking Soda (NaHCO3)
Citric Acid (H3C6H5O7)
250,000
10,000/g
20,000/g
Cork
Cardboard
50,000
12,000/cm2
Duct tape
Launch Pad
10,000/cm
Generously Donated
Procedure
To build the rocket itself a cork and one liter bottle were obtained. Three 6.75cm by
2.5cm fins were obtained and attached to the bottle using 3.9cm of duct tape. A paper nosecone
measuring 12cm tall with a radius of 8cm was created using 11cm of duct tape.
For the trial run a scale was used to measure 19.9g of citric acid and 26.2g. Using a
graduated cylinder 0.4L of water and was poured with the citric acid in the bottle. The baking
soda was wrapped in a paper towel and placed inside the rocket to launch.
For the final run a scale was used to measure 22.5g of citric acid and 29.7g of baking
soda. The baking soda and citric acid were placed in the rocket sans water and prepared to
launch. Using a graduated cylinder 0.5L of water was measured and poured into the rocket for
launch. The height was calculated from two separate trials.
Data
Table 2. Limiting Reactants in Moles and Height
Mass of
Moles
NaHCO3
NaHCO3
(Grams)
(Moles)
Trial Run
26.2
0.312
Final Run
29.7
0.354
Mass of
H3C6H5O7
(Grams)
19.9
22.5
Moles of
H3C6H5O7
(Moles)
0.104
0.117
Height
(Meters)
3.2
0.0
Data Analysis
The amounts of reactants were determined by subtracting the necessary costs by the
budget and using the rest. Then setting two equations equal to each other, the two values were
determined. The slope of the second equation was determined through trial and error, but, in
hindsight, it is proposed that because the ratio of moles is about 3:1, doubling the cost of citric
acid would change the ratio to about 3:2. It was discovered that these ratios annoyingly change
the higher or lower the numbers are. The amounts of reactants were then checked using
dimensional analysis.
Trial run:
Let x=Baking Soda and y= Citric Acid
1,500,000 – 840,000= 660,000 (at the time of calculation) so x + y ≤ 660,000. If y= 3/2x then x +
3/2x= 660,000 → x~ 262,000. If y= 3/2(262,000) then y~398,000. Finally 398,000/20,000=
19.9g of citric acid and 262,000/10,000= 26.2g of baking soda.
19.9g
H3C6H5O7
1
x
1mol H3C6H5O7
192.123g
x
3mol NaHCO3
1mol H3C6H5O7
x
84.007g
H3C6H5O7
1mol NaHCO3
=26.6g
NaHCO3
Amount of CO2 produced:
0.104mols H3C6H5O7
1
x
3mols CO2
1mol H3C6H5O7
22.4L
1mol CO2
x
=6.99L CO2
Final Run:
Let x=Baking Soda and y= Citric Acid
1,500,000 – 753,000= 747,000 so x + y ≤ 747,000. If y= 3/2x then x + 3/2x= 747,000 → x~
297,000. If y= 3/2(297,000) then y~450,000. Finally 450,000/20,000= 22.5g of citric acid and
297,000/10,000= 29.7g of baking soda.
22.5g
H3C6H5O7
1
x
1mol H3C6H5O7
192.123g
x
3mol NaHCO3
1mol H3C6H5O7
x
84.007g
H3C6H5O7
1mol NaHCO3
=29.7g
NaHCO3
Amount of CO2 produced:
0.117mols H3C6H5O7
1
x
3mols CO2
1mol H3C6H5O7
x
22.4L
1mol CO2
=7.86L CO2
Table 3. Cost Analysis of Trial Rocket
Material
Bottle
Cork
Paper Towel (2)
Cardboard (25.3125cm2)
Duct Tape (14.9cm)
Baking Soda, NaHCO3 (26.2g)
Citric Acid, H3C6H5O7 (19.9g)
Total Cost
Table 4. Cost Analysis of Final Rocket
Material
Bottle
Cork
Cardboard (25.3125cm2)
Duct Tape (14.9cm)
Baking Soda, NaHCO3 (29.7g)
Citric Acid, H3C6H5O7 (22.5g)
Total Cost
Cost (In U.S. Dollars)
250,000
50,000
70,000
303,750
149,000
262,000
398,000
1,482,750
Cost (In U.S. Dollars)
250,000
50,000
303,750
149,000
297,000
450,000
1,499,750
Conclusion
The purpose of this lab was to create a rocket that launched the highest. The trial rocket’s
distance was higher than the final launch. During the trial run a paper towel that was really thick
and did not allow the baking soda to completely react with the citric acid made the reaction
weak. Too much water was used giving the rocket less space for CO2 and less pressure to launch
out of the pad. The positive was that the rocket launched to a height of about 3.2 meters.
In the final run a new lunch technique was proposed; paper towels were rendered
obsolete by first mixing the powdered baking soda and citric acid and adding water to launch.
This was to use 100% of the reactants. With left over money 26.6g of baking soda became 29.7g
of baking soda and 19.9g of citric acid became 22.5g of citric acid. When water was added the
reaction proved to be too quick; the rocket was unable to be applied to the launch pad because
the cork fired directly it was put on. The amount of citric acid and baking soda aforementioned
filled the 1 liter bottle with CO2 extremely quickly.
There are numerous solutions for success in the future. Thin paper towels could be used
to delay the reaction but still employ most of the reactants. During the final launch too much
water delayed the application of the cork, so a reduced amount of water could allow less CO2 to
be released before launch. A larger bottle could have also allowed more time to set up, but still
launch with 7.86L of CO2. The final launch was a success in terms of the speed of reaction as it
launched faster than any other rocket.
Bibliography
"Atmospheric Flight." NASA Quest Aerospace. NASA Quest, n.d. Web. 17 Feb. 2016.
Bonuccelli, Courtney. "Hands-on Activity: Reaction Exposed: The Big Chill!" Teach Engineering. National Science
Foundation, 2009. Web. 17 Feb. 2016.
"NASA's Do-It-Yourself Podcast." NASA. NASA, n.d. Web. 17 Feb. 2016.
"Rocket Aerodynamics." Science Learning Hub RSS. Science Learning, 30 Nov. 2011. Web. 17 Feb. 2016.
"Water Rocketry - About Bottle Rockets." Space Flight Systems. NASA, n.d. Web. 17 Feb. 2016.
"Why Does Baking Soda and Vinegar React to Each Other?" UCSB Science Line. N.p., n.d. Web. 17 Feb. 2016.